This invention relates to a method for discriminating a human voice signal from any other sound signal, and also to a system for the method.
In the living environments of human beings, various sounds are existent. In recording and reproducing the sounds, it is required to record and reproduce them at high sensitivity and at high fidelity. In general, satisfying these requirements suffices.
In such general cases, all the sounds having entered, for example, a microphone have only to be equally amplified and reproduced. In some special uses, however, it becomes necessary to classify input signals depending on their properties or types and to subject a certain type of signals to processings different from those of the other types of signals.
This is, for example, to derive human voices from among noise or to pick up only the voices of an announcer separately from the other sounds such as music in case of recording the sounds of a radio or television broadcast. It is further considered to apply the above technique to devices for applying vibrations to the human body (body-felt vibration generator etc.) which have recently been proposed and put into practical use. Body-felt vibration is intended to mean a vibration which is felt by the human body due to the acoustic energy of a low sound frequency range component of sound; namely, a mechanical vibration produced from the acoustic energy by an acoustic energy-mechanical vibration converting system which applies the mechanical energy to the human body.
The body-felt vibration generator is a device in which, in order to give rise to the ambience with a sound reproducing equipment, signals of double (low) bass sound components of, e.g., below 150 Hz among amplifier output signals to be applied to loudspeakers (or headphones) are converted into mechanical vibrations so as to directly give the latter to the human body as body-felt vibrations, and the sounds and the body-felt vibrations of the double bass sound region are simultaneously given to an appreciator (a listener of music), thereby to intensify a heavy double bass sound feeling. The device has achieved effects principally for the appreciation of music.
It has been experimentally confirmed that, when the device is combined with sounds other than music, for example, documentary sounds and effect sounds attended with an earth tremor or the feeling of a shock such as the roaring of a gun, the running sound of a street car or steam locomotive, noise emitted when a big tree is cut down, explosion, and the running sounds and engine sounds of an automobile, tractor etc., the ambience and dramatic effects which cannot be obtained with conventional sound reproducing equipment can be brought forth.
When such device is incorporated into the cinema, television or the like, the real presence and numerous dramatic effects will be obtained. In this regard, a film drama, a television drama or the like is, in general, composed of the combination of human voices (conversation), music, and effect sounds.
Accordingly, when such sound signals are given to the appreciator in the form of the body-felt vibrations without performing any additional processing, big effects can be expected as to the sounds attended with the earth tremor and the feeling of a shock, while the body-felt vibrations are also produced as to the human voices (conversation). This has been experimentally revealed to cause a very unnatural feeling.
In order to produce good effects in the film drama, the television drama or the like, therefore, the advent of a device which is responsive to the musical and effect sounds but is not responsive to the human voices is desired.